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Oxytocin: More Than Just a “Love Hormone”

Oxytocin is a chemical produced in the brain during sex, childbirth, and breast-feeding. Research has shown that the so-called “love hormone” promotes bonding and other forms of social behavior.

But the idea that this neurotransmitter works as some sort of natural love potion is too simple. The effects of oxytocin may be more complex than we once thought.

Lei Xu, a psychologist at the Clinical Hospital of Chengdu, recently investigated the effects of oxytocin on partner preferences. Do we find different people more or less attractive after a dose of oxytocin?

Xu had 160 straight volunteers report to her lab. Half of these volunteers had a shot of oxytocin blasted up their nose; the other half received a placebo. Neither the volunteers nor the research assistant administering the doses knew whether each spray contained oxytocin or the placebo with no active ingredient. Afterward, the volunteers were unable to accurately guess whether they had received oxytocin or the placebo.

Next, the male volunteers were shown a series of portrait photographs of women, while the female volunteers saw photos of men. Each photo was paired with a statement about the person’s history of cheating. The person was described as someone who had committed a sexual or an emotional infidelity, or as someone who had never cheated.

Afterward, the volunteers indicated whether they would be willing to date each person.

Different effects on men and women

Although you might think that cheating is unattractive to both men and women, Xu found that 32% of men and 17% of women were interested in a short-term relationship with a former cheater. A cheater may not generally be considered a catch, but under certain circumstances men seem less perturbed than women by the prospect of an unfaithful partner, perhaps because men assume a woman who cheats will be easier to woo.

Xu also found that men who had been given oxytocin, compared to men who received the placebo, expressed a stronger desire to date women who had previously been unfaithful. There was no equivalent effect of oxytocin on the female volunteers, but oxytocin did increase women’s interest in long-term relationships with faithful men.

In short, oxytocin didn’t simply turn men and women lovey-dovey; instead, it promoted the pre-existing sex differences in men’s and women’s preferences for faithful and unfaithful partners.

Xu and her colleagues write in their paper that their findings supported their theory that “oxytocin would enhance current social and reproductive priorities in both sexes.”

Another finding was that women who had received a dose of oxytocin were more likely to remember the faces of men who were labeled faithful.